Sterilizing test device



Jan. 6, 1931. w, Ay s 1,788,104

STERILIZING TEST DEVICE Filed May 51 1930 INVENTOR W/LFRID HARGREA VESPatented Jan. 6, '1931 UNITED STATES "PATENT OFFICE STERILIZING TESTDEVICE Application filed May 81,

My invention relates to improvements in sterilizing test devices whichare particularly adapted for insert-ion in garments and dressings whichare to be treated in pressure sterilizers. The object of the inventionis to provide a sterilizing test device which will react to a desiredtemperature in such a manner that no doubt can exist in the mind of thesterilizer operative as to the condition of the 1 articles treated, andto provide a test device which when once used is so changed that itcannot be used again, as experience has definitely shown that devices ofthis nature when reused are misleading and dangerous. A further objectis to provide in such a device a written or printed word indicative ofthe condition of the articles in which it is placed, such indicationshowing the articles to be septic prior to sterilizing treatment and tobe sterile after.

The invention consists essentially of a sealed tube in which is encloseda label bearing such words as septic and sterile, the latter beingexcluded from view until the tube has been subject to a suitablesterilizing temperature and period, when the former. word becomesillegible and the latter exposed to view, as will be more fullydescribed in the following specification and shown in the accompanyingdrawings, in which s Fig. 1 is a general view showing the obverse sideof the-enclosed label.

Fig. '2 is-a view showing the reverse side of the label covered.

Fig. 3 is a view showing the reverse side oi the enclosed label aftersubjection to sterilizing heat.

In the drawings like characters of reference indicate correspondingparts in each figure. l I

The numeral 1 indicates generally a transparent glass tube sealed at itsends as at 2 and having attached thereto a thread 3 by which the tubecan be readily located in the '45 articles treated in the sterilizer.Inserted in the tube 1 is a label 4 preferably made of absorbent paper,upon the observe side of which is a word 5 such as septic. The ink usedin printing the obverse side is of a readily soluble nature or capableof being blurred when 1930. Serial No. 458,495.

subjected to a suitably high temperature. On the reverse side of thelabel a word 6 such as sterileis printed in an ink which is not solubleor subject to becoming illegible through being subjected to asterilizing heat. 'Aflixed to the reverse side of the label to excludethe word sterile from view is any suitable covering material 7 which iscapable of being rendered substantially transparent by subjecting it tosuitable heat, and I have found that acid benzoic is eminently suited tothis purpose since it is insoluble at a temperature of less than 240degrees Fahrenheit, but readily melts at this or higher temperatures andis so absorbed by the label that the word originally covered thereby isrendered quite clear and legible. V

The device is inserted between'the articles placed in the sterilizer.When sterilization is thought to be completed the device is withdrawnand if proper sterilization has been attained throughout the articlesthe device will have been subjected to the proper temperature also, theresult of such temperature being that the acid benzoic is changed froman opaque powder to a colorless solution which, when absorbent paper isused for the label, is absorbed by the label and serves to increase theillegibility of the word septic by dissolving the ink used in printingit, and causing said ink to spread.

If a non-absorbent'paper is used the acid benzoic on setting subsequentto cooling crys-- tallizes on the paper and over the word sterile, butdoes not revent the word from being clearly reada le and'properindication of the condition of the articles sterilized being displayed.

It will be obvious that while an indica- I that the device is new andhas not been subjected to sterilizing temperatures. It also follows thatany material which is opaque and is capable of undergoing such change asto disclose the printing on the obverse side a of the-label whensubjected to sterilizing heat will form a suitable substitute ,for theacid I benzoic herein mentioned.

What-I claim as my invention is: 1. A sterilizing control devicecomprisin a transparent body, an. absorbent printe label within thebody, an opaque covering for the rinted matter on the label, saidcovering being capable of being absorbed by the I label at sterilizingtemperatures. I 1 2. A sterilizin control device comprising atransparent body enclosing a label bearing a printed word indicative ofa septic condition and of ,a sterile condition, means normally excludinthe indication of sterili. 1 from view capable of change to expose suc cindication when the tube is subjected to sterilizing temperature and torender the word indicative of a septic condition permanently illegible.so 3. A sterilizin control device comprising a transparent bodyenclosing a label bearing a printed word indicatlvejof a septiccondition and of a sterile condition, lfieans' nor mally excludin theindication of sterilitz 25 vfrom view capa le of change to expose sueIndication when the tube is subjected'to sterilizing temperature and torender the word indicative of a septic condition permanently illegible,said word indicative of a. septic conao dition bein printed with amedium capable of being dissolved at a sterilizing temperature.

4. A sterilizing control device comprising a sealed transparent bodyenclosin an absorbent label printed on one side wit a word indicative ofsterility and on the other side with a word indicative of a. septiccondition, said label ha aflix'ed to the side bearing the indication osterility amaterial soluble 0 at about 250 degrees Fahrenheit andcapable of being' absorbed b the label whereby the pr nted matter on tat side of the label is permanently expo'm to view. 5. A sterilizingcontrol device comprising a sealed transparent body enclosing an.absorbent label printed on one side with water insoluble ink and on theother side with soluble ink, said label being covered on the insolubleink side with an opaque substance to obscure said printed matter andcapable of being dissolved at a temperature of about 250 de Fahrenheitand of being absorbed y the label, said substance when .dis- I solvedserving to d ssolve the soluble ink and ra der the matter printedtherewith illeg- 1 e. Dated at Vancouver, B. 0., this 14th day of May,1980.

- WILFRID HARGREAVES.

